Donor binding energies in a GaN/ZnGeN2 quantum well

Abstract

Binding energies of a donor atom within a GaN/ZnGeN2 quantum well structure have been investigated. Hydrogenic type wave functions are assumed and the Schrödinger and Poisson's equations are solved self-consistently. The binding energies of the donor states 1s and 2p± associated with the first subband in the quantum well and the transition energies between them are represented as a function of the quantum well width, the donor position and the external magnetic field. The ground state 1s and the excited states 2p± have maximum binding energies as much as 64 and 11 meV, occurring in quantum wells of widths 10 and 18 Å, respectively. The binding energies are found to be an asymmetric function of the donor position with respect to the quantum well center because of the asymmetry in the band profile introduced by the built-in electric field in the structure. An external magnetic field up to 10 T is included into the calculations and it is seen that the excited states show a small Zeeman splitting, very close to the bulk GaN value, because of the heavy effective mass of electron.